package org.mybatis.spring;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

import org.apache.commons.lang3.StringUtils;
import org.apache.ibatis.builder.xml.XMLMapperBuilder;
import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.session.Configuration;
import org.apache.log4j.Logger;
import org.springframework.core.NestedIOException;
import org.springframework.core.io.Resource;


/**
 * 刷新MyBatis Mapper XML 线程
 * @author baoyongtao
 * @version 2016-5-29
 */
public class MapperRefresh implements java.lang.Runnable {

	public static Logger log = Logger.getLogger(MapperRefresh.class);

	private static String filename = "/mybatis-refresh.properties";
	private static Properties prop = new Properties();

	private static boolean enabled;			// 是否启用Mapper刷新线程功能
	private static boolean refresh; 		// 刷新启用后，是否启动了刷新线程
	
	private Set<String> location;			// Mapper实际资源路径
	
	private Resource[] mapperLocations;		// Mapper资源路径
	private Configuration configuration;		// MyBatis配置对象
	
	private Long beforeTime = 0L; 			// 上一次刷新时间
	private static int delaySeconds;		// 延迟刷新秒数
	private static int sleepSeconds;		// 休眠时间
	private static String mappingPath;		// xml文件夹匹配字符串，需要根据需要修改

	static {
		
		try {
			prop.load(MapperRefresh.class.getResourceAsStream(filename));
		} catch (Exception e) {
			e.printStackTrace();
			log.error("Load mybatis-refresh “"+filename+"” file error.");
		}

		enabled = "true".equalsIgnoreCase(getPropString("enabled"));
		
		delaySeconds = getPropInt("delaySeconds");
		sleepSeconds = getPropInt("sleepSeconds");
		mappingPath = getPropString("mappingPath");

		delaySeconds = delaySeconds == 0 ? 50 : delaySeconds;
		sleepSeconds = sleepSeconds == 0 ? 3 : sleepSeconds;
		mappingPath = StringUtils.isBlank(mappingPath) ? "mappings" : mappingPath;

		log.debug("[enabled] " + enabled);
		log.debug("[delaySeconds] " + delaySeconds);
		log.debug("[sleepSeconds] " + sleepSeconds);
		log.debug("[mappingPath] " + mappingPath);
	}

	public static boolean isRefresh() {
		return refresh;
	}

	public MapperRefresh(Resource[] mapperLocations, Configuration configuration) {
		this.mapperLocations = mapperLocations;
		this.configuration = configuration;
	}

	@Override
	public void run() {

		beforeTime = System.currentTimeMillis();

		log.debug("[location] " + location);
		log.debug("[configuration] " + configuration);

		if (enabled) {
			// 启动刷新线程
			final MapperRefresh runnable = this;
			new Thread(new java.lang.Runnable() {
				@Override
				public void run() {
					
					if (location == null){
						location = new HashSet<String>();
						log.debug("MapperLocation's length:" + mapperLocations.length);
						for (Resource mapperLocation : mapperLocations) {
							String s = mapperLocation.toString().replaceAll("\\\\", "/");
							s = s.substring("file [".length(), s.lastIndexOf(mappingPath) + mappingPath.length());
							if (!location.contains(s)) {
								location.add(s);
								log.debug("Location:" + s);
							}
						}
						log.debug("Locarion's size:" + location.size());
					}

					try {
						Thread.sleep(delaySeconds * 1000);
					} catch (InterruptedException e2) {
						e2.printStackTrace();
					}
					refresh = true;

					log.info("========= Enabled refresh mybatis mapper =========");

					while (true) {
						try {
							for (String s : location) {
								runnable.refresh(s, beforeTime);
							}
						} catch (Exception e1) {
							e1.printStackTrace();
						}
						try {
							Thread.sleep(sleepSeconds * 1000);
						} catch (InterruptedException e) {
							e.printStackTrace();
						}

					}
				}
			}, "MyBatis-Mapper-Refresh").start();
		}
	}

	/**
	 * 执行刷新
	 * @param filePath 刷新目录
	 * @param beforeTime 上次刷新时间
	 * @throws NestedIOException 解析异常
	 * @throws FileNotFoundException 文件未找到
	 * @author ThinkGem
	 */
	@SuppressWarnings({ "rawtypes", "unchecked" })
	private void refresh(String filePath, Long beforeTime) throws Exception {

		// 本次刷新时间
		Long refrehTime = System.currentTimeMillis();

		// 获取需要刷新的Mapper文件列表
		List<File> fileList = this.getRefreshFile(new File(filePath), beforeTime);
		if (fileList.size() > 0) {
			log.debug("Refresh file: " + fileList.size());
		}
		for (int i = 0; i < fileList.size(); i++) {
			InputStream inputStream = new FileInputStream(fileList.get(i));
			String resource = fileList.get(i).getAbsolutePath();
			try {
				
				// 清理原有资源，更新为自己的StrictMap方便，增量重新加载
				String[] mapFieldNames = new String[]{
					"mappedStatements", "caches",
					"resultMaps", "parameterMaps",
					"keyGenerators", "sqlFragments"
				};
				for (String fieldName : mapFieldNames){
					Field field = configuration.getClass().getDeclaredField(fieldName);
					field.setAccessible(true);
					Map map = ((Map)field.get(configuration));
					if (!(map instanceof StrictMap)){
						Map newMap = new StrictMap(StringUtils.capitalize(fieldName) + "collection");
						for (Object key : map.keySet()){
							try {
								newMap.put(key, map.get(key));
							}catch(IllegalArgumentException ex){
								newMap.put(key, ex.getMessage());
							}
						}
						field.set(configuration, newMap);
					}
				}
				
				// 清理已加载的资源标识，方便让它重新加载。
				Field loadedResourcesField = configuration.getClass().getDeclaredField("loadedResources");
				loadedResourcesField.setAccessible(true);
				Set loadedResourcesSet = ((Set)loadedResourcesField.get(configuration));
				loadedResourcesSet.remove(resource);
				
				//重新编译加载资源文件。
				XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(inputStream, configuration, 
						resource, configuration.getSqlFragments());
				xmlMapperBuilder.parse();
			} catch (Exception e) {
				throw new NestedIOException("Failed to parse mapping resource: '" + resource + "'", e);
			} finally {
				ErrorContext.instance().reset();
			}
			log.debug("Refresh file: " + mappingPath + StringUtils.substringAfterLast(fileList.get(i).getAbsolutePath(), mappingPath));
			if (log.isDebugEnabled()) {
				log.debug("Refresh file: " + fileList.get(i).getAbsolutePath());
				log.debug("Refresh filename: " + fileList.get(i).getName());
			}
		}
		// 如果刷新了文件，则修改刷新时间，否则不修改
		if (fileList.size() > 0) {
			this.beforeTime = refrehTime;
		}
	}
	
	/**
	 * 获取需要刷新的文件列表
	 * @param dir 目录
	 * @param beforeTime 上次刷新时间
	 * @return 刷新文件列表
	 */
	private List<File> getRefreshFile(File dir, Long beforeTime) {
		List<File> fileList = new ArrayList<File>();

		File[] files = dir.listFiles();
		if (files != null) {
			for (int i = 0; i < files.length; i++) {
				File file = files[i];
				if (file.isDirectory()) {
					fileList.addAll(this.getRefreshFile(file, beforeTime));
				} else if (file.isFile()) {
					if (this.checkFile(file, beforeTime)) {
						fileList.add(file);
					}
				} else {
					System.out.println("Error file." + file.getName());
				}
			}
		}
		return fileList;
	}

	/**
	 * 判断文件是否需要刷新
	 * @param file 文件
	 * @param beforeTime 上次刷新时间
	 * @return 需要刷新返回true，否则返回false
	 */
	private boolean checkFile(File file, Long beforeTime) {
		if (file.lastModified() > beforeTime) {
			return true;
		}
		return false;
	}

	/**
	 * 获取整数属性
	 * @param key
	 * @return
	 */
	private static int getPropInt(String key) {
		int i = 0;
		try {
			i = Integer.parseInt(getPropString(key));
		} catch (Exception e) {
		}
		return i;
	}

	/**
	 * 获取字符串属性
	 * @param key
	 * @return
	 */
	private static String getPropString(String key) {
		return prop == null ? null : prop.getProperty(key);
	}

	/**
	 * 重写 org.apache.ibatis.session.Configuration.StrictMap 类
	 * 来自 MyBatis3.4.0版本，修改 put 方法，允许反复 put更新。
	 */
	public static class StrictMap<V> extends HashMap<String, V> {

		private static final long serialVersionUID = -4950446264854982944L;
		private String name;

		public StrictMap(String name, int initialCapacity, float loadFactor) {
			super(initialCapacity, loadFactor);
			this.name = name;
		}

		public StrictMap(String name, int initialCapacity) {
			super(initialCapacity);
			this.name = name;
		}

		public StrictMap(String name) {
			super();
			this.name = name;
		}

		public StrictMap(String name, Map<String, ? extends V> m) {
			super(m);
			this.name = name;
		}

		@SuppressWarnings("unchecked")
		public V put(String key, V value) {
			// ThinkGem 如果现在状态为刷新，则刷新(先删除后添加)
			if (MapperRefresh.isRefresh()) {
				remove(key);
				MapperRefresh.log.debug("refresh key:" + key.substring(key.lastIndexOf(".") + 1));
			}
			// ThinkGem end
			if (containsKey(key)) {
				throw new IllegalArgumentException(name + " already contains value for " + key);
			}
			if (key.contains(".")) {
				final String shortKey = getShortName(key);
				if (super.get(shortKey) == null) {
					super.put(shortKey, value);
				} else {
					super.put(shortKey, (V) new Ambiguity(shortKey));
				}
			}
			return super.put(key, value);
		}

		public V get(Object key) {
			V value = super.get(key);
			if (value == null) {
				throw new IllegalArgumentException(name + " does not contain value for " + key);
			}
			if (value instanceof Ambiguity) {
				throw new IllegalArgumentException(((Ambiguity) value).getSubject() + " is ambiguous in " + name
						+ " (try using the full name including the namespace, or rename one of the entries)");
			}
			return value;
		}

		private String getShortName(String key) {
			final String[] keyparts = key.split("\\.");
			return keyparts[keyparts.length - 1];
		}

		protected static class Ambiguity {
			private String subject;

			public Ambiguity(String subject) {
				this.subject = subject;
			}

			public String getSubject() {
				return subject;
			}
		}
	}
}
